1. Technical Field
The present invention generally relates to a semiconductor integrated circuit, and more particularly, to a power tracking circuit and a semiconductor apparatus including the same.
2. Related Art
A semiconductor device is applied with power from an external source and uses the power to drive an internal circuit. Accordingly, it is important to provide a stable external voltage to obtain a stable and reliable result from a semiconductor device.
FIG. 1 is a view showing a situation in which a fail occurs according to a variation in the level of an external voltage VDD in the conventional art.
In the case of A (i.e. pass), although the level of the external voltage VDD slightly decreases, since the slight decrease is not such an extent to exert an influence on the operation of a semiconductor device, the semiconductor device as a whole normally operates. Also, in the case of B (i.e., pass), although the level of the external voltage VDD abruptly decreases by a large extent, since the level of the external voltage VDD is quickly recovered, the semiconductor device as a whole normally operates.
However, in the case of C (i.e., fail), since the level of the external voltage VDD decreases by a large extent and the decreased level is retained for a lengthy time, an error is likely to occur in the operation of the semiconductor device as a whole.
In general, in the voltage generation block of a semiconductor device, a voltage variation is detected and a detection result is fed back to allow a constant voltage to be generated. For example, the semiconductor device has a voltage detection circuit which detects that an external voltage changes and an internal voltage drops below a predetermined reference voltage, to allow the internal voltage to be recovered.
Nevertheless, by the voltage detection circuit, a reaction is unnecessarily made even when the level of the external voltage VDD abruptly decreased is quickly recovered as in the case of B in FIG. 1. This may complicate the operation of the semiconductor device and may serve as a factor for causing an error in the operation of the semiconductor device.